Leg length adjusting apparatus



June 16, 1959 v R. F. DERBY ETAL .2,890,824

LEG LENGTH ADJUsTING APPARATUS Filed Aug. 26, 1954 United States "Patent O 2,890,824 LEG LENGTH ADJ USTIN G APPARA'IUIS- Richard F. Derby, West Concord, and Arthur Biery, Pine Island, Minn.

Application August 26, 1954, Serial No. 452,288

8 Claims. (Cl. 22S- 63) This invention relates to apparatus for attachment to :an article having support legs for maintaining such article in substantially level position and for maintaining the support legs thereof in substantially upright position irregardless of the contour of the supporting surface upon which such article is placed, and more specifically this invention relates to apparatus for substantially automatically adjusting the length of the legs of such an article depending upon the contour of the supporting surface upon which the legs are placed.

Many articles, such as stepladders, lawn chairs and tables, saw horses, extension ladders and the like are primarily designed for use out-of-doors and are to be placed upon the ground which frequently has an irregular contour. When such articles are placed upon such an irregularly contoured supporting surface not all of the support legs of such an article will engage the ground and therefore the article will assume a tilted position to cause all of the legs thereof to engage the ground and lend support thereto.

In the past some types of apparatus of the class described have been devised but have some serious disadvantages which prevented such types of apparatus from coming into widespread use, Generally such types of apparatus employ a leg-adjusting cord to substantially simultaneously adjust the relative position of the adjustable extension members of such apparatus. A major disadvantage of many of the known types of apparatus of the class described is that the weight of the article supported and the weight of any load placed on such an article is carried by the leg-positioning cord. Obviously .such cords are thereby subjected to substantial wear and 4strain and, of course, when such a cord breaks as` a result of the wear the leg-adjusting apparatus will substantially collapse to cause sudden and often disastrous tilting of the article supported thereby.

Another of the serious disadvantages of many types of apparatus of the class described is that `the locking of the leg extension portions of the apparatus is not positive at all times. ln these types of apparatus the leg eXtension portions are locked when a load is carried by the article supported by the legs, and when such load is removed, the leg-extension portions become unlocked and are permitted to retract to cause tilting and shifting of the article. This is especially disadvantageous when such types of apparatus are used with a stepladder where the leg-extension portions are securely locked when a man is on the ladder but become unlocked when he gets olf the` ladder, as onto a roof. If the ladder shifts before he again places his weight on the top of the ladder, a serious accident is very likely to occur when he places his Weight upon the tilted ladder. i

Therefore, it is to the solution of these and other disadvantages to which our invention is directed along with the inclusion therein of other novel features.

A general object of our invention is to provide a new 'and improved apparatus of relatively simple and inexpensive construction and operation for adjusting the lengths 2,890,824 Patented June 16, 1959 of the support legs of an article depending upon the contour of the surface or terrain upon which the article is to be placed to maintain such legs in their normal substantially upright position.

Another object of our invention is to provide novel apparatus of the class described which will positively lock the support legs of such an article in extended position when the weight of such article is carried thereby and will be quickly released to permit adjusting of the length of the legs when the weight of the article is removed from such support legs.

Still another object of our invention is to provide improved apparatus of the class described which will provide oppositely directed shifting of the extension portions of the support legs when only one of the extension portions engages the ground and which will lock the leg eX- tension portions in fixed vertical relation when both of the same engage the supporting surface and tend to shift upwardly `with relation to the support legs.

These and other objects and advantages of our invention will more fully appear from the following description made in connection with the accompanying drawings Wherein like reference characters refer to the same parts throughout the several views and in which:

Fig. 1 is a front elevation View of a pair of support legs embodying our invention and being partly broken away to show details thereof;

Fig, 2 is a detail View taken on a horizontal plane Substantially at 2--2 of Fig. 1;

Fig. 3 is a detail section View taken on a horizontal plane substantially at 3 3 of Fig. 1;

Fig. 4 is a detail elevation view, partly in section, taken on a substantially vertical plane at 4-4 of Fig. l; and

Fig. 5 is a detail sectional elevation view taken substantially at 5-5 of Fig. 4, and showing a portion of the apparatus of Fig. 1 in unlocked position.

As shown in Fig. l we provide a pair of substantially `upright extendible and retractable support legsl 10 and 11 which may be secured to an article such as a saw horse or extension ladder to support the same. Support legs 10 and 11 include support rails 12 and 13 or rail members which are rigidly interconnected by any suitable means, such as the article supported thereby, to positively maintain support rails 12 and 13 in Xed relation relative to each other.

Each of the support rails 12 and 13 are provided with a pair of apertures each being aligned with a corresponding aperture in the other support rail. Tubular members 14 and 15 are disposed in spaced apart relation between rail members 12 and 13 and are inserted into the aligned apertures thereof to provide a tubular interconnection therebetween. Tubular members 14 and 15 may be secured in the rail members 12 and 13 by any suitable means such as by crimping the end portions thereof, to form external retaining flanges 14a and 15a respectively.

A pair of rollers 16 having concavely curved guiding peripheral surfaces are provided, in the form shown, at the lower terminal portions of tubular member 14 and are suitably journalled to permit rotation thereof about an axis extending transversely of tubular member 14 and `rail members 12 and 13.

Guiding means are provided on the lower' end portions 12a and 13a of rail members 12 and 13 and in the form shown such guiding means comprise guide elements 17 and 18 in the form of eye bolts connected to the respective rail members 12 and 13 by any suitable means such as nuts 17a and 18a.

Support legs 10` and 11 also include a pair of upright rigid extension members 19 and 20 which, in the form shown, are constructed of a tubular metal material, and which are guided by guide elements 17 and 18 respective- 1y for vertical sliding movement adjacent to `and in spaced relation with the respective support rails 12 and 13. EX- tension members 19 and 2.0 extend downwardly beyond the lower end portions 12a and 13a of the respective rail members 12 and 13 to engage the supporting surface S which may be irregularly contoured. Extension members 19 and 20 are provided at the lower end portions with enlarged feet 21 and 22. Ball sockets 19a and 20a are provided in the lower end portions of the extension members 19 and 20 to receive and swivelly and swingably mount the respective ball connections 21a and 22a of feet 21 and 22 respectively. A pair of stabilizing members 23 and I24, as best shown in Fig. 3 are secured to the upper end portions of the extension members 19 and 20 respectively. Stabilizing elements 23 and 24 are provided with laterally extending guiding flanges 23a and 24a which ,are disposed in proximity with the respective support rails 12 and 13 to be guided thereby to prevent turning of extension members 19 and 20 about their respectivelongitudinal axes.

A pair of locking elements 25 and 26, which in the form shown are constructed of a ferrous metal material, are swingably ymounted on the respective support rails 12 vand 13, and in the form shown are mounted between the respective guide elements 17 and 18 thereon. The locking elements 25 and 26 have locking rings 25a and 26a and elongated shanks 25b and 2617 with slightly enlarged shoulder portions 25C and 26C interposed therebetween. The interior opening of the ring portions 25a and 26a Vmay be slightly oblong in shape and are of such size to receive the respective Vextension members 19 and 2,0 in close fit-ting relation, allowing the same to slide freely therethrough. Rings 25a and 26a are disposed in laterally outstanding relation with the respective support rails and are provided with inner and outer gripping portions which, when locking elements 25 and 26 are swung in yan upward direction, engage and frictionally grip the respective extension members 19 and 20. Tapered apertures 12b `and v13b -provide a restricted opening in an-outward direction through Vthe respective support rails 12 and 113 to receive the shank portions 25b and 26b of locking elements 25 and 26 respectively. The yupper portions of apertures 12b and 13b are substantially horizontal ,to -preclude locking elements V25 and 26 from swinging -in a downward direction and the lower portions of said apertures are inclined to permit swinging of locking elements '25 and 26 upwardly into a locking position. Actuating elements 27 and 28, which constitute magnets, are mounted in the respective side rails 12 and 13 above the Vrespective locking elements to exert ,a force thereon to lswing the same into substantially horizontal position wherein .the extension members 19 and 20 will be unlocked. Of course a tension spring might be substitutedfor suehmagnets v27 and 28 as shown.

Locking actuators 29 and 30 comprise, lin the form Shown, metal plates, each of which are similarly constructed. As .bestshown in Fig. 4, locking plate 36 is provided with `a pailof spaced apart elongated guide apertures `or openings 30a which receive Aand are guided by the `Shanks `of :eye bolts l17 to `permit restricted vertical movement of y.plate `3.0. fPlate 30 Valso is provided with another aperture 3,0b kin the upper end portion thereof which is substantially .aligned with the opening `of tubular member 15 and the respective aligned apertures of support .rails 12 and 13. Locking ,plate 30,is also provided with an oblong laterally extending opening 30C in the central `portion qthereof between .openings 3.0: to receive the shank ,portion 25,11 andfshoulder portion 25C yof `locking element 25 therethrough. In closely Vspaced relation with and below opening 30C, an out-turned rigid lip 30d is `provided for engaging the `shoulder portion 25a` of locking element 25. I

A exible interconnection 31 ,is secured to each of the extension members 19 vand A2,0 `and extends therebetween thrOLlh the apertuld support Vrails 12 and 13 to be guided thereby, the upper portion 31a of flexible nterconnection 31 `extending through tubular member 14 and the lower portion 31b extending through the tubular member 15 and through the aligned apertures 29b and 30b of the respective locking actuators 29 and 30. In the form shown the flexible interconnection comprises an elongated flexible element such as a cord or flexible cable which is guided by the rollers 16 and which is secured to the stabilizing members 23 and 24 of the respective ex tension members 19 and 20.

Operation In operation the article to which the extendible and retractable support legs 10 and 11 are secured will be generally lifted to move the same into a desired position. When the support legs 10 and 11 are raised, the weight of the extension members 19 and 20 is carried by the upper portion 31a of the cord 31 and the extension members 19 and 20 are both shifted downwardly slightly relative to the respective `support .rails 12 and 13 when tension is applied'to the -liexible cord 31. This will cause a slight downward shifting of the lower portion 311; of cord 31 which permits restricted downward shifting ,of locking actuator plates 29 and 30. Downward movement of the actuator plates `29 and l30 causes their respective out-turned 'lip portions 29d and 30d to disengage from the locking elements 25 and 26. The slight downward shifting of extension members 1'9 and 20 will also cause aswinging of locking elements 25 and 26 in downward direction causing the same to assume a substantially horizontal position substantially as shown in Fig. 5 wherein the extension members 19 and l2() are free to slide.

When the support legs 10 and 11 are again lowered toward the ground, one of the `extension members 19 and 2 0 will engage the irregularly contoured supporting surface before the other .extension member engages said surface. If only extension member 19 engages the support,- ing surface, it will .be shifted upwardly with respect to support lrail 12 to relieve tension on the -upper portion 31g of `cord 3.1.which allows extension member 20 to shift downwardly. The lower portion 31b of cord 31 may exert a 4slight downwardly directed V.pulling force .of extension `member, 20 to aid in shifting thereof -in a downward direction. Supporting legs 10 and 11 will be manually held in an upright position while extension member .19 is shifting upwardly and being retracted and while extension `member 20 is being extended in a downward direction.

After `some `upward shifting of extension member 19 and downward shifting of extension member 20, exten- Sion member 20 will also .engage the supporting surface. When ythe weight of the support legs 10 and 11 and o f the article held thereby is placed upon the extension members 19 and 20, .there will be a slightly downward shifting of support rails 12 and 13 'with respect to the corresponding extension members 19 and 2010 relieve the tension .in the upper vportion 31a of ilexible cord 31 and to tighten the .lower portion 31h of cord'31. The ltightening of the lower yportion 31b of cord 31 is accomplished by a slightllpward shifting thereof which causes a slight upward-:shifting of veach of the locking actuators 29' and 30g-and a corresponding lupward shifting of the out-turned lips '29d and 30d `thereof. Upward shifting of said lips causes them to engage the shoulder portions 25e and 26e-of locking elements 25 land 26 to cause the same to be swung upwardly. The innerand outer locking portions yof the1locking elements engage and .grip the extension members 219 and 20 in Alocking relation vand prevent upward shifting thereof with respectto thelcorresponding suppgrltzrails :12 and 13.

Qfcgurse fit is obvious Ithat the gudeelements 17 and 18 could be replaced by a suitably arranged tubularguide housing which in addition `to guiding vwould make the working apparatus .more t weather-,proof to i, prevent ,deter rioration thereof.

It will be seen that we have provided a new and improved apparatus of relatively simple and inexpensive construction and operation for adjusting and fixing the lengths of the support legs of an article to suitable lengths so as to maintain such legs in their normal upright position and to maintain such an article in level position without regard to the contour of the supporting surface upon which the article is to be placed.

It twill also be apparent that we have provided novel apparatus for substantially simultaneously adjusting the dilferent lengths of a pair of support legs when said legs are placed upon an irregularly contoured surface and which, when both of said legs engage s-uch a surface, will positively lock such legs to restrict subsequent retraction thereof and to thereby maintain such legs in sub- :stantially normal upright position.

It will also be noted that we have provided improved leveling mechanism for an article to be placed upon an irregularly contoured supporting surface which mechae nism is positively locked when the weight of the article is carried thereby and is quickly and surely released when the weight of the article is removed therefrom to provide ready and easy adjustment of the length of the legs of such an article.

It will, of course, be understood that various changes may be made in the form, detail, arrangement and proportion of the parts without departing from the scope of our invention which consists of the matter described herein and set forth in the appended claims.

What we claim is:

1. In a leveling apparatus for supporting an article on an irregularly contoured surface, the combination of a pair of extendible and retractable support legs adapted to carry such an article, each of said legs including an upright rail member rigidly secured to the rail member of the other leg, and each of said legs including an extension member disposed adjacent the corresponding rail member and extending downwardly therebeyond to engage such a supporting surface, guide means slidably interconnecting said extension members with the corresponding rail members to permit relative vertical shifting thereof, a pair of locking elements each respectively interposed between a corresponding rail member and extension member, each of said locking elements being fulcrumed on one of said members for vertical swinging and -having oppositely facing gripping portions disposed on opposite sides of the corresponding extension member for frictionally engaging the opposite sides of a corresponding extension member upon tilting movement of said locking elements to positively lock the locking elements solely to the corresponding extension member, said locking elements including a portion for supporting said rail members, and a continuous exible interconnection having upper and lower portions slidably carried by and extending between said rail members and having Vertically movable side portions securely attached to each of said extension members, whereby said flexible interconnection will produce with displacement of one of said extension members oppositely directed displacement of the other extension member when the same engage such an irregular surface, whereupon the legs may be locked in position to maintain the same in substantialy upright position.

2. The structure recited in claim l and including actuating members secured to the support rails adjacent to said locking elements and each of said actuating members exerting a force on the corresponding locking elements in a direction to swing the gripping portions thereof out of locking engagement with the corresponding extension members when the support leg is raised to remove the weight thereof from the extension member.

3. The structure `recited in claim 1 and including a pair of stabilizing elements each fixedly secured to a :respective extension member and extending laterally thereof into close proximity `with the corresponding support frail to engage and be guided thereby to prevent turn'-l ing of said extension member to preclude slipping in the frictional engagement between the extension member and the corresponding locking ring.

4. In apparatus for leveling an article to be placed upon an irregularly contoured surface, the combination of a pair of upright support rails attachable to such an article, a pair of extension members respectively disposed adjacent corresponding rails and extending downwardly therebeyond for engaging such a surface, guide means slidably interconnecting said support rails and the corresponding extension members to permit relative vertical shifting thereof, an elongated exible element slidably carried by and extending between said support rails and having gvertically movable portions, secured to each of said extension members, both of said vertically movable portions moving upwardly in response to upward movement of the extension members, a pair of rigid locking elements fulcrumed on respective support rails for vertical swinging and having oppositely facing gripping portions disposed on opposite sides of the corresponding extension member for frictionally engaging the opposite sides of a corresponding extension member upon tilting movement of said locking elements to positively lock the locking elements solely to the corresponding extension member, said locking elements including a portion for supporting said rail members, and actuating interconnections respectively connected with the vertically movable portions, said iiexible element and said locking elements and swinging said locking elements upwardly into gripping relation on said extension members lwhen the extension members simultaneously engage such an irregular surface and are shifted` upwardly with respect to said support rails.

5. In a leveling apparat-us for supporting an article on an irregularly contoured supporting surface, the combination of a pair of rigidly interconnected upright support rails, each having spaced apart apertures and having lower end portions and each adapted to be secured to such an article, a pair of rigid extension members and each extending downwardly beyond the lower end portion of said support rails for engaging such an irregularly contoured supporting surface, a number of lguide elements eacih slidably interconnecting one of said support rails and the corresponding extension member in spaced relationship, a pair of locking rings, means mounting one of said locking rings on each of said support rails to swing in a vertical direction and to extend outwardly therefrom in surrounding relation with the corresponding extension member, each of said locking rings having inner and outer gripping portions disposed on opposite sides of the extension member and being swingable upwardly into frictional :gripping engagement therewith to thereby restrict vertical shifting thereof relative to the corresponding support rail, a pair of locking actuators each being guided on one of said support rails for restricted vertical movement, means engaging lthe corresponding locking ring to produce vertical swinging thereof, aligned apertures in said support rails each of said locking actuators having an aperture therein substantially aligned with one of the apertures in the corresponding support rail, and an elongated exible element secured to said extension members and having an upwardly directed portion threaded through the apertures of said support rails and having a downwardly directed portion extending through the aligned apertures of said locking actuators and said support rails and producingwith displacement of one of said extension members, oppositely directed displacement of the other extension member, and said elongated flexible element producing with simultaneous upward shifting of both of said extension members, upward shifting of said locking actuators to swing said locking rings into locking frictional engagement with the extension members to thereby restrict upward shifting thereof relative to said support rails.

6. The structure recited in claim 5 and said locking asedses linssbeing constructed et e'ferrousnietei materiel and e. neit 0f. nregnets-mennted in Sadfsnppnrt rails adjacent. tofsaisi. nieansrnennting, said loekn-rn rings and. exerting;

a force thereon to swing the locking rings. out, of locking engegenrent when the slippen. rails are raised teeense the Weightof said extension members to move the same dewnnerdiy- 7. Ina leveling apparatusfor supporting an articleon en irregularly eenienred: snrfase. the een.rbinznien ef.` a

pair ef. rigidly intereenneeted depending rail membersattachabletosuch an article, `apar ofelongated extension members respectively disposed. adjacentV corresponding rail membersf and extending1 downwardly therebeyorrd',r

guide means. slidably interconnecting said rail members and their eenespending extensien r'nernbersr e. pair ef. locking elements each fulcrurned for vertical swinging enaresneeiive rail member and. haring. epnesitely. facing gripping "portions disposed on oppositeY sides ofthe core responding extension member. forv frictionally. engaging the opposite sides of a corresponding eXtension member upon tilting movement of said locking elements to positively. lock thellock-ing elements solely tothe corresponding err'- tension member, saidlooking4 elements including a portion for supporting said rail members, actuatingv mecl'ianism seid.k rail. members, whereby te leek said members teseiner.

8- In nleyelingv apparatus for sunnerting. an artieleen en irregularly; eontQured the earnleination` f, a.

pair ef'rigidl'y intere nneeted depending. reiirnenrbersl having lower end Pern nsl andbeing attaehable te. sneh; an article, e neit ef vertiealiy slidebl'e. extension members respectively disposed adjacent corresponding trail, mm: bers and extendingl downwardly therebeyend, .'guide Ineens Sliderblyfintereenn gsaid rail members and the eer:

responding extension members., apairof locking elements, each fuilcrumed on onerof said rail members for verticalv Swinging and neving oppesitely facing gripping portions disposed on opposite sides of the corresponding extension member for frictionally enga-gingthe opposite. sides of a corresponding extension member upon tilting movement.

of said locking elements to positively lock the locking elements solelyv to the corresponding. extension member,

Seid leekngelements ineindingn portion for supporting- Seid rail members, end.. Operating Ineens intereen'neeting. Seid 'leekine ,elements for simultaneously. shifting the same into gripping positions and including a. connection with each of' saidextension; members for actuating said locking elements when said extension membersare simultaneously shifted upwardly with respect to said rail members'.

References Cited-in the file of this patent UNITED STATES PATENTS 2,330,825 Hoit Oct. 5, 1943 2,366,829- Biery Jan. 9, 1945 2,555,036v I-IillStt-:dA May 279, 1951 2,608,794 Matter Sept. 2, 1952 

